Sensitivity Analysis of Safety Factors Based on Model of AviationReciprocating Engine Turbocharging System

Aviation reciprocating engines dominant the low-power general aviation power, but air intake method of most engines is natural aspiration that engine performance will decrease significantly in high-altitude environments. Assembling the turbocharging system, the high-altitude performance of engines can be effectively restored and the working ceilings of general aircraft can be significantly improved. While improving engine performance, safety of turbocharging system should be paid enough attention. The Response Surface Methodology explores the influence of factors on the response value by fitting the function relationship of multiple quadratic regression equations, and avoids the limitation of ignoring the interaction between factors. Sobol factor analysis is a global sensitivity analysis method that calculates the response index of there sponse value by matrix calculation to quantify the influence of parameters on the response value. In this paper, model-based system safety analysis method is combined with the "V" type safety analysis process, the response surface methodology and the Sobol factor sensitivity analysis method to compare turbo charging system performances of the sensitivity of different safety influencing factors by constructing the engine model and fitting the equation for global sensitivity analysis, in order to improve the level of safety analyzing. A methodical case of sensitivity analysis of safety influencing factor of the engine quasi-dimensional model built by Rotax914 as a prototype is given using the proposed method in this paper. Results show that the sensitivity index of altitude is much higher than other factors. The sensitivity index of the diameter of the intake valve is higher than that of the diameter of the exhaust valve, but in the same quantity. The effective length of the air filter in a normal operating environment has almost no impact on the turbo charging system. Therefore, the scope of the safety influencing factors can be adjusted based on the analysis during the actual running, reducing the uncertainty of critical factors, allowing an efficient and intuitive safety analysis.